Recovery of lubricating oil from solvent extracts



July 1U, 1951 w. c. JONES, JR 2,560,448

RECOVERY oF LUBRICATING on. FROM soLvRNT RxTRAcTs Filed May 15, 1948 29)(gnomes A wur-:R 7 INVENTOR.

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Patented July 10, 1951 UNITED STATES PATENT OFFICE RECOVERY F LUBRICATIGOIL FROM SOLVENT EXTRACTS William C. Jones, Jr., Baytown, Tex., assgnor,by

mesne assignments, to Standard Oil Development Company, Elizabeth, N.J., a corporation of Delaware Application May 15, 1948, Serial No.27,265

Prior to the present invention, it has been known to extract lubricatingoil fractions with ysolvents having the ability to concentrate the morearomatic constituents as opposed to the more paraflinic constituents,the latter being the more desirable as a lubricating oil fraction. Ithas also been proposed by the prior art workers to re-extract solventextracts with solvents such as those employed in the preliminary solventextraction to recover therefrom material having lubricating oilqualities approaching thev quality of the solvent raffinate. The priorart teachings have shown that while a lubricating oil may be recoveredfrom solvent extracts by re-extraction, the quality of theoil recoveredis not as good as that obtained in the primary extraction.

It has also been known to contact hydrocarbons l with porousadsorbentssuch as silica gel, which is incompletely dehydrated silicicacid containing 'Water in an amount from about 3 to 7%. Silica gel hasbeen used to remove aromatics from hydrocarbons boiling in the gasolineand kerosene boiling ranges. It has also been known to employ silica gelto remove sulfur compounds from fractions boiling through the keroseneboiling range. However, this work has not resulted in commercialsuccess.

The demands imposed by the last great warY have resulted inunprecedented consumption of crude petroleum. The premium crude oils,which contain appreciable quantities of high quality lubricating oil,are being consumed more rapidly.

than new sources of them can be found. Therefore, it is important thatthe supplies of the high quality lubricating oils be augmented by moreeflicient utilization of what is available or by provision of newsources for these high quality, materials.

Therefore, it is the main objectv of the present invention to provide aprocess in Which solvent extracts of lubricating oils are contacted withsilica gel to obtain high quality lubricating oil fractions.` i

Another object of the present invention is to recover from lubricatingoil solvent Vextracts high quality lubricating oil fractions which..heltoiore Inl Claims. (Cl. 196-147) freeing of solvent, is admixed witha hydrocarbon diluent, such as a paranic hydrocarbon boiling in thegasoline boiling range, and contacted with an excess of silica gel,which is incompletely dehydrated silicic acid containing from about 3 to7% Water. The silica gel preferentially adsorbs the non-paraflinicconstituents from the mixture of light hydrocarbon diluent and solventextract, allowing high quality lubricating oil fractions, whichheretofore were unrecoverable, to be obtained. Following the adsorptionof the undesirable components from the solvent extract, these materialsare removed from the adsorbent, silica gel, by contacting the materialcontaining the adsorbed matter with an aromatic hydrocarbon solvent orother suitable solvent which effectively desorbs the adsorbed materialand allows the recovery of the latter and makes the silica gel suitablefor regeneration for reuse in the process. Regeneration may beaccomplished by steaming followed by a drying cycle with hot air orother heated gases. Y

The silica gel employed in the practice of the present invention isavailable on the market, the commercial grades having particle sizessuicient to be retained by 28 mesh up to 200 mesh being eminentlysuitable in the practice of the present invention. However, silica gelhaving particle sizes up to 350 mesh may be used. The amount of silicagel employed should be in excessof the amount of oil which is contactedwith it. For example, in a single pass operation, a range from about 2to 1 to about 30 to 1 of silica gel to oil ratios gives satisfactoryresults. A ratio of about 4 to 1 of silica gel to aromatic constituentscontained in the oil is preferred.

In order to obtain throughput at a satisfactory rate, it may benecessary to contact a bed of silica gel with the oil at an elevatedpressure. For example, a pressure slightly above atmospheric to about300 pounds per square inch gauge carbons adsorbed material issues fromcontacting zone f I f byline and is discharged by' line 2B into a may beused with a preferred range of about to 135 pounds per square inchgauge.

Temperatures to be employed in the practice of the present invention maybe substantially atmospheric, but higher temperatures may be used. Forexample, a temperature of about 60. to about 200z F. may besatisfactory. However, the temperature will depend on the viscosity ofthe oil used and the amount of dilution with the parafflnic diluent.Ordinarily, when dilutingthe oilwith equal volumes of paranic diluent,atemperature in the range from about y80" to 100 F. will besatisfactory. A`

The parafllnic diluent employed in the practice of the present inventionshould be substantially aromatic free. A suitable fraction to employwill boil from about 100' F. to about '115' F. provided no aromatics arecontained therein. It is also within the scope of my invention to employsubstantiallyrpure hydrocarbon fractions such as normal hexane, normalheptane, the octanes, vancleven the higher members of the samehomologous series such as the nonanes and the like. As a general rule,the boiling range of the paranic diluent should be suii'lciently diierlent from the boiling range ofthe solvent extract being treated to alloweasy separation by distillation.

tives of benzene and toluene such as ethylbenzene, propylbenzene, andthebutylbenzenes, and the like. Any one of these aromatic hydrocarbons ormixtures thereof may be used as a desorbent to remove the adsorbedmaterial from the silica gel.

The invention will be further illustrated by reference to the drawing inwhich the sole ligure presents a flow diagram of one mode of practicingthe invention.

Referring now Vto the drawing, numerals I'I and I.2,'r.espectively,designate contacting zones containing beds I3 and I4 of silica gel whichis indicated by the shaded portion. These beds are supported on suitablegrills I5 and I0.

A Vsolvent extract such as a .phenol extract of a lubricating oil`fraction .is introduced into the -system by line I1 .and is admixedwith a hydrocarbon diluent introduced thereto by line I3 controlled byvalve I-9. The hydrocarbon diluent ordinarily will be a parafiinichydrocarbon such as.normal heptane. The mixture flows through line I.1into an incorporator or other mixing device20 where intimate contactingbetween the I parainic diluent and solvent extract occurs. The admixturethen discharges from incorporator 20 by line 2| from whence it may berouted to either contacting zone II or I2. For purposes of illustration,it is assumed that the admixture is directed to contacting zone I I,valve 22 in line 23 being in the open position while valve 24 in' line2| is in the closed position. The admixture of parainc diluent andsolvent extract flows downwardly through bed I3 in contacting zone I Iwhich eiectively removes from the solvent extract the hydrocarbons andother organic compounds having ring structure, leaving the parafnic andthe more nearly parailinic-like hydrosubstantially unadsorbed. Theunstripping Zone 21 which may be a distillation tower or a series ofdistillation towers provided with suitable internal baffle equipmentsuch as bell cap trays and packing to allow intimate contact betweenliquids and vapors. In this particular instance, stripping Zone 21 isshown as a single distillation tower equipped with a heating meansillustrated by coil 28 by way of which temperatures and pressures inzone 21 are adjusted. Theconditions are maintained in zone `21-toobtainas an overhead fraction the hydrocarbon diluent injected into the systemby line I8. .This overhead Vfraction is removed from zone 21 by line 29,is cooled and condensed in cooler 30 and then returned to be used foradmixture with additional quantities of solvent extract introduced byline I8. Withdrawn from the bottom of stripping zone 28 is a fractionincluding high viscosity index lubricating oil constituents which areremoved by line 3|. This material, without further treatment, issuitable for use as a high grade lubricating oil having a viscosityindex above 100.

After a period of operation, the bed I3 of silica gel in contact zone IIloses its ability to remove undesirable components from the solventextract. When these conditions obtain, valve 22 in line23 is closed andvalve 24 in line 2| is opened. Valve 32 in line 20 is also closed. Thus,it will be seen that contacting zone I will be removed from the systemand contacting zone I2 placed on the operating stream with the mixtureof hydrocarbon diluent and solvent extract owing through line 2| andvalve 24 vinto contacting zone I2 whence it contacts bed I4 and has itsundesirable constituents removed therefrom by adsorption. The unadsorbedmaterial discharges from zone I2 by line 33 into line 26 and thence intostripping zone 21 where it follows the cycle as has been described.

It now becomes necessary to .remove the adsorbed materials from bed I3.'Ihis may be accomplished by introducing an aromatic wash solvent of thetype illustrated into the system by opening valve 34 in line 35 andallowing it to flow by lines 36 and 31 controlled by valve 38 into line23 and downwardly through bed I3 in contacting zone III.A The materialadsorbed on the silica gel is desorbed by the washing action of thearomatic solvent and discharges from zone I3 by .line 25 into line 26controlled by valve 32 and thence into line 39 controlled by valve 40into a second stripping zone 4I which, similar to stripping zone '21,may be a series of distillation towers, but for convenience isillustrated as a single tower provided with a heating means illustratedby a coil 42. It will be understood, of course, that stripping zone 4Iwill be provided with all necessary equipment for suitable contactbetween vapors and liquids. In stripping zone 4I temperatures andpressures are adjusted l to remove overhead by line 43 the `aromaticwash solvent introduced into the system vby line 35. This material iscooled and condensed in cooler 44 and admixed with the wash solvent inline 36 to wash additional quantities of material from the bedundergoing the washing cycle.

After substantially all of the adsorbed material has been removed fromthe'bed I3, it is then subjected to a steaming operation, the flow ofaromatic solvent being terminated by closing valve 34. Steam isintroduced into line 36 from a source not shown by opening valve 45,valve 38 in line 31 being closed and valve 46 in line 36 also being intheclosed position. Valve 32 inY line.26 is also in the closed position.Steam ris then vline 43 for recycling with the wash solvent removed fromstripper 4|,as has been described. The bed I3 in zone II is now incondition to be dried and this is accomplished by introducing heated airor other gases by line 54 controlled by valve 55. The heated air or gasfollows substan- -tially the flow of steam with the gases being -ventedfrom the top of separator 50 by line 56 controlled by valve 51.

When the bedv|4 in contacting zone I2 loses its ability to removeundesirable constituents from the solvent extract, it may be subjectedto a similar cycle of washing, steaming, and drying with a heated gas ashas been described with reference to the bed I3. When contacting zone I2is taken out of the operating system, valve 24 'in line 2| is closed andvalve 58 in line 33 is closed. Aromatic wash solvent is introduced byway of line 35 into line 35 and flows thereby into line 2I by openingvalve 46. "hydrocarbon ilows downwardly through zone I2 The aromatic andwashes bed I4 of adsorbed material. The

Iwashed material ows from zone I2 by lines 33 -and 59 into line 39controlled by valve 40 which fdischarges it into stripping zone 4I wherethe -aromatio hydrocarbons are recovered and recycled as has beendescribed. It will be understood, of course, that valve 60 will beclosed, preventing admixture of the unadsorbed material flowing in line25 with the desorbed material owing through line 59. Following thewashing operation the bed I4 is then steamed by introduction of steam byopening valve 45 in line 36 and opening valve 6I in line 62 allowing thesteam to flow by lines 36, 62, and 33 upwardly through bed I4 andoutwardly therefrom by line 63 controlled by valve 54 and thence intoline 49 and settler 55 where water is separated therefrom and thehydrocarbons are routed by lines 53 and 43 back into the washing cycle.After introduction of steam has been terminated, the bed I4 may then bedriedby introducing hot air ,or heated gas by opening valve 55 inline-54.

6 l cosity index of #5.' This material was unsuitable for use as alubricating oil stock, and prior to the present invention, had beensegregated for employment as a feed to a thermal cracking unit. Asillustrative of the magnitudeof' this'material, one commercial plant hasaccumulated over an operating period of 5 days some` 4300 barrels ofthis -5 viscosity index solvent extract.

A portion of this material was then percolated, after dilution with anequal volume of normal heptane, downwardly through a 52 foot columncontaining silica gel of 28 to 200 mesh. The percolation was conductedwith a silica gel to oil ratio of 4 to 1, a pressure in the rangebetween 35 to 135 pounds per square inch, and a temperature lrangingfrom 81 to 96 F. The percolate was collected in fractions and blended. Alubricating oil fraction amounting to the first l23.2% of the materialcharged was freed of solvent by stripping and on testing was found tohave a viscosity index of 108.6. This recovered lubricating oil of thehigh viscosity index mentioned was water white in color and is suitablefor use as a lubricating oil.

It is believed that the solvent extraction of lubricating oils removesnatural inhibitors and concentrates them in the extract. It is believedthat the silica gel does not remove the natural inhibitors from asolvent extract and that they remain in the percolates that are madeavailable in the present invention as high quality lubricating oilmaterial.

As illustrative of the magnitude of the savings possible in the practiceofthe present invention, lubricating oil having a viscosity index of108.6 has a value of about $10 per barrel. It will thus be seen thateven though the percentage of the lubricating oil recoverable by thepractice of the present invention is of the nature of 25%, the magnitudeof the savings is relatively large.

The invention has been described and illustrated by examples in whichsolvent extracts of lubricating oil fractions are contacted with beds ofsilica gel. It will be understood by the skilled workman that it will bepossible to practice the present invention by forming a mixture of thesolvent extract with the parafnic diluent and then forming a slurry ofthe silica gel in the adand may be vented from settler 50 by line 56controlled by valve 51. After the regeneration has been completed thebed I2 may be placed back Y on the operating cycle by closing valveGI,valve 55, Valve B4, and opening valves 24 and 58, line 59 having beenisolated by closing valve 63. It will be seen from the foregoingdescription taken with the drawing that a continuous process has beenprovided whereby a plurality of beds on operation and regenerationcycles may be used to remove valuable hydrocarbons from solvent extractsby contacting with silica gel.

In order tc illustrate the invention further, reference will now be hadto an example in which a motor oil fraction from Panhandle crude wasextracted with phenol to obtain a raffinate corresponding to 870% byvolume of the charge to the phenol extraction. This raffinate had aviscosity index of 102. The extract, after freeing of solvent, wastested and found to have a vismixture and allowing the silica gel toremain in contact with the admixture until the undesirable constituentsare adsorbed thereon. The silica gel containing adsorbed components ofthe extract mixture may then be separated by gravity settling, ltration,or other settling methods well known to the art.

In the several examples, reference has been made to contacting themixture of solvent extract and paraflinic diluent with a bed of silicagel. It will be understood that a plurality of beds may be employed. Forexample, it may be desirable to use two or more beds in the practice ofthe present I invention so the operation may be conducted on vdexsolvent extract of a lubricating oil and a light parafiinic hydrocarbon,said solvent extract containing high viscosity index components forminga bed of silica gel having a particle size in the range between 28 and350 mesh, contact-ing the mixture with the bed of silica gel at avtemperature in the range between 60 F. and 200 F. with said silica gelbeing in excess of said extract to cause selective adsorption by thesilica gel of low viscosity index constituents in said mixture,`removing unadsorbed mixture from contact with said bed, and recoveringfrom said unadsorbed mixture by distillation high viscosity indexlubricating oil fractions.

2. A method in accordance with claim 1 in which the light parainichydrocarbon is normal heptane and the solvent extract is a phenolextract.

3. A method in accordance with claim 1 in which the tempera-ture is inthe range between 80 F. and 100 F.

4. A method for recovering high viscosity index lubricating oilfractions from a low viscosity index solvent extract of a lubricatingoil which comprises adrnixing a low viscosity index phenol extract of alubricating oil fraction in equal volumes with normal heptane, saidphenol extract containing high viscosity index components forming a bedof silica gel having a particle size in the range between 28 and 200mesh, contacting the admixture with said bed at a temperature in therange between 80 F. and 100 F., maintaining a ratio of silica gel to oilin the range between 2 to l and 30 to 1 to cause selective adsorption bythe silica gel of low viscosity index constituents in said admixture,removing unadsorbed admixture from contact with said bed, and distillingsaid unadsorbed admixture to recover normal heptane and high viscosityindex lubricating oil fractions.

5. A method for recovering high viscosity index lubricating oilfractions from a low viscosity index solvent extract of a lubricatingoil which comprises admixing said extract with a light paraiiinichydrocarbon, said solvent extract containing high viscosity indexcomponents forming a plurality of beds of silica gel having a particlesize in the range between 28 and 200 mesh, contacting the admixture withat least a first of said plurality of beds at a temperature in the rangebetween 60 F. and 200 F. with said silica gel being in excess of saidextract to cause selective adsorption of low viscosity indexconstituents in said admixture until said first bed has substantiallylost its ability to remove low viscosity index constituents from saidadmixture, terminating contact of said admixture with said first bed,contacting said admixture with at least a second of said plurality ofbeds at a temperature in the range between 60 F. and 200 F. said silicagel being in excess of said extract to cause selective adsorption of lowviscosity index constituents in said admixture, recovering unadsorbedadmixture from contact with said beds, distilling said unad- 'sorbedmixture to recover high viscosity index components, regenerating saidrst bed, andreturning it to contact additional quantities of saidadmixture.

6. A method 'in accordance with claim 5 in which the light parainichydrocarbon is normal heptane and the solvent extract is a phenolextract.

7. A method in accordance with claim 5 in which the temperature is inthe range between F. and 100 F.

8. A method for recovering high viscosity indexlubricating oil fractionsfrom solvent extracts of lubricating oils which comprises forming a.mixtureof a low viscosity index solvent extract of a lubricating oiland a light parafnic hydrocarbon, said solvent extract containing highviscosity index components forming a bed of silica gel having a particlesize in the range between 28 and. 200 mesh, contacting the mixture withthe bed of silica gel at a temperature in the range between 60 F. and200 F. with said silica gel being in excess of said extract to causeselective adsorption by the silica gel of low viscosity indexconstituents in said mixture, removing unadsorbed mixture from contactwith said bed, `re generating said bed by contacting it with a lowboiling aromatic hydrocarbon, and recovering from said unadsorbedmixture by distillation high viscosity index lubricating oil fractions.

9. A method in accordance with claim 8 in which the low boiling aromatichydrocarbon boils in the gasoline boiling range.

l0. A method for recovering high viscosity index lubricating oilfractions from a low Viscosity index solvent extract of a lubricatingoil whi-ch comprises admixing said extract with a light parafnichydrocarbon, said solvent extract containing high viscosity indexcomponents, forming a slurry of silica gel having a particle size in therange between 28 and 200 mesh in the admixture at a temperature in therange from 60 F. to 200 F. with said silica gel being in excess of saidextract to cause selective adsorption by the silica gel of low viscosityindex yconstituents in said admixture, removing silica gel containingadsorbed low viscosity index constituents from the slurry, andrecovering high viscosity index lubricating oil fractions from theunadsorbed admixture by distilling same.

WILLIAM C. JONES, J n.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 2,106,767 Smith Feb. 1, 19382,117,602 Bulkley May 17, 1938 2,441,572 Hirschler et al May 18, 19482,487,805 Hermanson Nov. 15, 1949

1. A METHOD FOR RECOVERING HIGH VISCOSITY INDEX LUBRICATING OILFRACTIONS FROM LOW VISCOSITY INDEX SOLVENT EXTRACTS OF LUBRICATING OILSWHICH COMPRISES FORMING A MIXTURE OF A LOW VISCOSITY INDEX SOLVENTEXTRACT OF A LUBRICATING OIL AND A LIGHT PARAFFINIC HYDROCARBON, SAIDSOLVENT EXTRACT CONTAINING HIGH VISCOSITY INDEX COMPONENTS FORMING A BEDOF SILICA GEL HAVING A PARTICLE SIZE IN THE RANGE BETWEEN 28 AND 350MESH, CONTACTING THE MIXTURE WITH THE BED OF SILICA GEL AT A TEMPERATUREIN THE RANGE BETWEEN 60* F.A ND 200* F. WITH SAID SILICA GEL BEING INEXCESS OF SAID EXTRACT TO CAUSE SELECTIVE ADSORPTION BY THE SILICA GELOF LOW VISCOSITY INDEX CONSTITUENTS IN SAID MIXTURE, REMOVING UNADSORBEDMIXTURE FROM CONTACT WITH SAID BED, AND RECOVERING FROM SAID UNADSORBEDMIXTURE BY DISTILLATION HIGH VISCOSITY INDEX LUBRICATING OIL FRACTIONS.